Thermofluids (Determine surface temperature)

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SUMMARY

The discussion focuses on determining the heat flux and duct surface temperature for air flowing through a thin pipe. Given parameters include a mass flow rate of 0.05 kg/s, an inlet temperature of 103°C, and an outlet temperature of 77°C after 5 meters of travel. The heat transfer coefficient is specified as 6 W/m²K at an ambient temperature of 0°C. The calculated heat transfer rate is 1313 W, using the equation q = mcp(Ti - To) with cp for air set at 1010 J/kgK.

PREREQUISITES
  • Understanding of heat transfer principles, specifically convection and conduction.
  • Familiarity with the specific heat capacity of air (cp = 1010 J/kgK).
  • Knowledge of heat transfer coefficients and their application in thermal analysis.
  • Basic proficiency in applying thermodynamic equations for heat transfer calculations.
NEXT STEPS
  • Learn about calculating heat flux using q'' = q/A for surface area determination.
  • Study the derivation and application of the heat transfer coefficient for internal flow in ducts.
  • Explore the implications of varying surface conditions on heat transfer rates.
  • Investigate the effects of pipe diameter and flow rate on thermal performance in fluid systems.
USEFUL FOR

Students and professionals in mechanical engineering, particularly those specializing in thermodynamics and heat transfer analysis, will benefit from this discussion.

Michael24
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Homework Statement


Air flows at a mass flow rate(m) of 0.05kg/s in a thin pipe with a diameter of 0.15m. The air enters the pipe at (Ti)103 deg celc and cools to(To) 77 deg celc after traveling 5 m in the pipe. The heat transfer coefficient between the duct outer surface and the ambient air at Tamb = 0 deg celc is ho = 6W/m2K.

Determine the heat flux(W/m2 and the duct surface temperature at x = 5m. The duct wall is thin and conduction effect can be neglected.

Homework Equations


q''[W/m2] ...Might need this equation ??

The Attempt at a Solution



q [W] = mcp(Ti-To) = 1313 W where cp = 1010 J/KgK for air flowing through pipe.

If I'm not told that the surface heat flux is constant can I still apply the equation above? Also, without knowing surface conditions such as constant surface heat flux or constant surface temperature is this problem solvable?
 
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Have you learned how to determine the heat transfer coefficient for the internal flow? If so, please tell us how you would proceed.

Chet
 

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